Exhaled breath is commonly used in alcohol testing and today's technology makes it possible to perform on-site breath testing with legally defensible results using infrared spectroscopy.
Testing DNA and testing for drugs, whether abused or used therapeutically, generally requires the taking of blood or urine samples for testing. Hair, sweat, and oral fluid can also used for drug and DNA testing. Blood sampling is invasive and requires medically trained personnel, and the test subject is often transported to a hospital or other specialized facility for sampling. These procedures are time and effort consuming. The collection of urine samples may also be considered intruding on personal integrity. Other problematic issues related to samples and specimens taken from a subject include risk of disease transmission or infection and the risk of the subject exchanging samples or using a clean sample from another subject to avoid detection of illicit drugs.
The need to provide a non-invasive, not-specimen based apparatus, system and/or method for detecting the presence (i.e. qualitative) or determining the quantitative amount of a substance in a subject is at least partially met by the invention disclosed in PCT Application No. PCT/EP2012054180, the contents of which are incorporated herein by reference for all purposes. PCT/EP2012054180 discloses an apparatus, system and method for sampling the exhaled breath of a subject for a drug substance and/or a biomarker. Aerosols from the lungs of the subject are collected on a sampling membrane and then analyzed for the presence and optionally the amount of one or more nonvolatile compounds.
In DE19718924, breath is in a specific exhalation device conveyed through a fiber fleece. Large aerosol particles are caught in the fiber fleece by condensation. The device of DE19718924 comprises several valves which increase the resistance to blow through the device. The fiber fleece is removed from the housing, folded into the upper part of a centrifugal tube. The fiber fleece can be contaminated by this procedure. A standard elution solution, such as ELISA buffer or salt solutions, is added to the tube. A total amount of lung substances from the caught aerosol is determined from the eluate obtained. The determined total amount of lung substances allows for diagnosis and therapy of diseases, such as asthma. However, the disclosure of DE19718924 is not very detailed. The total amount of lung substances obtained as a result is not very specific and allows only coarse diagnostics and doubtful therapy based on such diagnostics. Sampling times in a range of 5-15 minutes are rather long and consistency of results over the range is not demonstrated. The method and device of DE19718924 do not appear to be very efficient and have a limited applicational range. Despite DE19718924 being published in 1998, no major improvement has been disclosed during 15 years. Hence a long felt need exists for improvement.
The present invention provides a method for eluting nonvolatile compounds from a sampling membrane in such a way that the eluted compounds are easily assayed. The present method improves the yield and consistency of recovery of nonvolatile compounds from sampling membranes used to collect aerosols from exhaled breath.